// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2014 Benoit Steiner <benoit.steiner.goog@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_CXX11_TENSOR_TENSOR_INITIALIZER_H
#define EIGEN_CXX11_TENSOR_TENSOR_INITIALIZER_H

#if EIGEN_HAS_VARIADIC_TEMPLATES

#include <initializer_list>

namespace Eigen {

/** \class TensorInitializer
 * \ingroup CXX11_Tensor_Module
 *
 * \brief Helper template to initialize Tensors from std::initializer_lists.
 */
namespace internal {

template<typename Derived, int N>
struct Initializer
{
	typedef std::initializer_list<typename Initializer<Derived, N - 1>::InitList> InitList;

	static void run(TensorEvaluator<Derived, DefaultDevice>& tensor,
					Eigen::array<typename traits<Derived>::Index, traits<Derived>::NumDimensions>* indices,
					const InitList& vals)
	{
		int i = 0;
		for (const auto& v : vals) {
			(*indices)[traits<Derived>::NumDimensions - N] = i++;
			Initializer<Derived, N - 1>::run(tensor, indices, v);
		}
	}
};

template<typename Derived>
struct Initializer<Derived, 1>
{
	typedef std::initializer_list<typename traits<Derived>::Scalar> InitList;

	static void run(TensorEvaluator<Derived, DefaultDevice>& tensor,
					Eigen::array<typename traits<Derived>::Index, traits<Derived>::NumDimensions>* indices,
					const InitList& vals)
	{
		int i = 0;
		// There is likely a faster way to do that than iterating.
		for (const auto& v : vals) {
			(*indices)[traits<Derived>::NumDimensions - 1] = i++;
			tensor.coeffRef(*indices) = v;
		}
	}
};

template<typename Derived>
struct Initializer<Derived, 0>
{
	typedef typename traits<Derived>::Scalar InitList;

	static void run(TensorEvaluator<Derived, DefaultDevice>& tensor,
					Eigen::array<typename traits<Derived>::Index, traits<Derived>::NumDimensions>*,
					const InitList& v)
	{
		tensor.coeffRef(0) = v;
	}
};

template<typename Derived, int N>
void
initialize_tensor(TensorEvaluator<Derived, DefaultDevice>& tensor,
				  const typename Initializer<Derived, traits<Derived>::NumDimensions>::InitList& vals)
{
	Eigen::array<typename traits<Derived>::Index, traits<Derived>::NumDimensions> indices;
	Initializer<Derived, traits<Derived>::NumDimensions>::run(tensor, &indices, vals);
}

} // namespace internal
} // namespace Eigen

#endif // EIGEN_HAS_VARIADIC_TEMPLATES

#endif // EIGEN_CXX11_TENSOR_TENSOR_INITIALIZER_H
